The five loss of motor

America at the beginning of this century and the emergence of the so-called "super efficient motor more efficient". In general, high efficiency motor compared with the ordinary motor loss, average fell about 20%, and the super efficient motor than theordinary motor loss average dropped more than 30%. Because the loss of super efficient motor is high efficiency motors have a further decline, so for the long-term continuous operation, load rate high, energy saving effect is more obvious. In order to improve the efficiency of the motor from the ordinary to ultra high performance motor,in addition to measures to increase the silicon steel sheet and copper consumption and reduce fan size, measures must also be taken in the application of new materials,motor manufacturing process and optimization design, in order to control the cost and satisfy the motor structure size limit. Many foreign enterprises to actively carry outresearch in these aspects, and made some progress. General electrical steel sheetprocessed into iron core pressing into the base, a substantial increase in consumption of iron, and the British Brook company Hansen and steel factory, the successful application of a new developed electrical sheet steel, processed into iron core made of electric motor, iron loss in little change before and after the processing. Japan's Toshiba Co is one of the main suppliers American efficient motor and ultra high efficiency motor. The company claims that due to the improvement of themanufacturing process and the use of new materials, the high efficiency motor costs fell by 30%, including the measures taken: the application of special line tools,improve the stator slot full rate, increasing the cross-sectional area of copper wire; to improve the manufacturing precision, shorten the length of the gap, the copper lossfrom the excitation current and its induced decreases; using rotor slot insulationtechnology, reduce the stray loss; using laser core lamination tool, the iron lossdecrease. As the copper than the resistivity of aluminum decreased about 40%, so if the cast copper rotor instead of cast aluminum rotor, total loss of the motor can significantly decrease. These years, the International Copper Association in AmericanDepartment of energy's support, carried out the process of copper pressure casting,has now been solved high temperature die material and die casting process related issues, thus making it possible for more economical mass production of cast copper rotor motor. In 2003 June, the German SEW Eurodrive company has been using thisdie casting technology successfully launched a series of gears using cast copperrotor motor. Italy science and technology education department and related agencies to carry out performance data comparison test project of cast copper rotor and a cast aluminum rotor. The project by the Italy LAFERT motor company, Thyssen

Krupp Steel Corp and the French FAVI cast Copper Co cooperation. The test does not change in stator, rotor slot, only to change the magnetic material and the length of the case, our data show that, by using cast copper rotor, can make the motor to reduce energy consumption by 15% ~ 25% in the original basis, the motor efficiency can be increased by 2% ~ 5%. But because the rotor resistance reduction will causethe starting torque decline, it should be the other parameters adjustment in the design, so that to improve efficiency at the same time, to meet the other main performance index.

Rotor loss

The motor rotor I^2R losses are mainly related to the rotor current and rotor resistance, energy saving and corresponding methods are mainly:

(1) reduces the rotor current, which can be considered from two aspects to improve the voltage and the motor power factor;

(2) increasing the rotor slot section area;

(3) to reduce the resistance of the rotor winding, such as the use of coarse wire andlow resistance of the material, it is meaningful to the small motor, because of the smallmotor is generally cast aluminum rotor, if the cast copper rotor, the total loss of the motor can be reduced by 10% ~ 15%, but the current cast copper rotor required formanufacturing high temperature and the technology has not yet universal, its cost is higher than the cast aluminium rotor 15% ~ 20%.

Stator loss

The main means of motor stator I^2R loss reduction in practice commonly usedmethod is:

(1) try to shorten the length of the end of stator winding, stator end winding loss totalloss the windings of 1/4 ~ 1/2, reduce the winding end length, can improve the efficiency of motor. Experiments show that the end length decreased 20%, 10%decline the loss;

(2) increase the stator slot tankful rate of low pressure and small motor, the effect is better, the optimum application of winding and insulation size, high wire cross-sectional area can increase the stator tankful rate;

(3) increase the stator slot cross-sectional area, in the same stator outer diameter of the circumstances, increase the stator slot cross-sectional area will reduce the area of a magnetic circuit, the flux density increase of tooth.

Stray loss

Now the understanding of stray losses are still in the research stage, nowadays somereducing stray loss of main methods:

(1) through the improvement of stator winding design to reduce the harmonic;

(2) by heat treatment and precision processing to reduce the short circuit of rotor surface;

(3) improved rotor slot matching design and fitting to reduce the harmonic, increase the stator and rotor tooth and the rotor slot is designed into a chute, using series connected sine winding and spreading of winding and the short winding can greatly reduce the high harmonics; using magnetic slot mud or magnetic slot wedgealternative insulation slot wedge, with magnetic slot mud filled motor stator the iron core slot of the tradition, is a effective method to reduce the additional stray loss;

(4) the rotor groove surface insulation process.

Iron loss

Can be reduced by the following measures the consumption of iron:

(1) heat treatment and manufacturing technology, the iron chip processing after theresidual stress will seriously affect the motor loss, silicon steel sheet processing,cutting direction, punching shear stress effects on the core loss of the larger. Along the rolling direction of silicon steel sheet cutting, and the punching of heat treatment,can reduce 10% ~ 20% of the loss and other methods to achieve;

(2) by the guide of cold rolled silicon steel sheet magnetic good property of reducinghysteresis loss;

(3) reduce the iron chip thickness to reduce the induction current losses, such as the use of cold rolled silicon steel sheet instead of hot rolled silicon steel sheet can reduce the silicon steel sheet thickness, but the thin iron chip will increase the number and the motor iron chip manufacturing chen;

(4) uses high performance iron chip insulation coating;

(5) reduce the magnetic density, increase the length of the iron core on magnetic flux density is reduced, but the motor with a concomitant increase in the amount of iron.

Wind abrasion

To the people the attention it deserves, it accounts for about 25% of total loss ofmotor. Friction losses are mainly caused by the sealing bearing and can be reducedby the following measures:

(1) the use of efficient lubrication system and lubricant;

(2) the use of advanced seal technology, if there is no spring new sealing condition of the report, said by effectively reducing the contact pressure and the shaft, can make the 45mm diameter shaft to rotate to 6000 RPM reduces the loss of nearly 50 W; the flow loss is caused by the cooling fan and rotor ventilation groove, used to produce airthe flow of cooling motor. The flow loss typically accounts for about 20% of total loss of motor. Fluid mechanics and heat transfer of the whole motor analysis is complicated, even more complicated than analysis of space shuttle components, fluidmechanics and heat transfer design good will greatly enhance the cooling efficiency ofmotor and reduce the flow loss.

(3) reduce the axial size, but the need to meet the requirements of the output torqueand rotor dynamics;

(4) the use of high performance bearing;